It is well recognized that proper and uniform spacing of seed in the furrow is essential to maximizing crop yield. Recent advances in metering technology have resulted in seed meters capable of singulating seed extremely well under field planting conditions. However, in order to achieve optimum consistency and accuracy of seed spacing, attention must be paid to every detail of the operating condition of the entire planter row unit, including the seed delivery tube, which can significantly effect seed spacing after the seeds are discharged by the seed meter.
Conventional seed tubes are made of injection molded plastic or polymer materials that can wear rapidly when in contact with the steel opening disk. As the tube wears and the plastic sidewall becomes thin, the sidewall is more susceptible to bending inward which can effect the ideal trajectory of the seed as it exits the seed tube. Additionally or alternatively, wearing of the sidewall can cause a “burr” or lip to form at the egress end of the tube, also effecting the ideal trajectory of the seed as it exits the tube.
Conventional seed delivery tubes are susceptible to wear for a variety of reasons. As identified above, one of the primary reasons for seed tube wear is contact with the furrow opening disks. Seed tube-to-opener disk contact may occur under a number of circumstances. For example, as the opening disks wear and shims are removed in order to maintain the proper disk-to-disk spacing, the disks tend to shift inward until they are in contact with the lower edge of the seed tube. This contact with the seed disk can cause significant wear to the seed tube.
Another reason contact with the opener disks can occur may be due to improper alignment of the seed tube within the row unit. For example, seed tubes generally have a seed sensor secured with tie straps to the middle portion of the tube. The bulk of the seed sensor wires and straps can push or bias the seed tube off-center, causing it to rub against the opener disk.
Yet another reason for tube-to-disk contact resulting in wear of the seed tube may be due to the opening disks flexing inward during planting operations, especially during planting in no-till conditions.
In addition to effecting seed spacing, high wear rates of conventional seed tubes also cause the operator to incur high replacement costs as the tubes need to be replaced yearly in order to maintain optimum performance.
Attempts have been made to minimize seed tube wear problems by various methods, all of which have heretofore been directed toward some means of holding the tube in the center of the row unit opener. One such attempt at keeping the tube in the center of the opener consists of a molded plastic bracket as shown in U.S. Pat. No. 5,664,507 to Bergland. This bracket snaps in place over the seed tube guard to keep the tube centered. Experience has shown that this bracket does not eliminate contact between the tube and opener disks and therefore does not solve the wear problem.
Another recent attempt to keep the seed tube centered within the opener is a seed tube guard that has a bracket welded to it that effectively creates wings to constrain or hold the seed tube within in the center of the row. The wings of the welded bracket design can bend during use thereby failing to eliminate the wear problem. Yet another design is an investment-cast seed tube guard wherein the wings are an integral piece of the part.
Still other efforts by original equipment manufacturers have attempted to utilize a sheet metal bracket mounted to the opener disk shaft to hold the tube in the center of the opener.
All of the foregoing these attempted improvements are predicated upon the supposition that if the tube is held in the center of the furrow, it will not contact the disks and therefore will not wear. Rather than attempting to ensure the seed tube remains centered within the opener, a more ideal solution is to ensure that the seed tube does not significantly wear if and when the seed tube does eventually contact the opener disks. Minimizing wear of the seed tube such that the trajectory of the seed is not affected, provides the advantage of increased performance and reduced maintenance costs and ensures optimum consistency and accuracy of seed placement within the furrow.